Study: Nuke Site Issues Pose Blast Risk

Leaking radioactive waste tanks, design flaws, and poor safety practices at a nuclear tank farm in Washington could lead to an explosion and other threats to public health and safety, a nuclear safety board warned this week.

The Defense Nuclear Facilities Safety Board outlined its perspective on safety concerns with Hanford Tank Farms, unresolved technical issues related to the design of the Waste Treatment and Immobilization Plant, and the state of the safety culture at Hanford.

Photos: Department of Energy

Hanford Tank Farms started producing plutonium for World War II bombs in the early 1940s. Now it holds over 50 million gallons of radioactive waste in underground tanks, which are starting to leak.

The Hanford Site is located in southeastern Washington on 586 square miles of desert. In the early 1940s, the plant was used to produce plutonium for the bomb that ended World War II, according to its website. The federal government used the site for portions of the Manhattan Project, working secretively to develop atomic weapons.

Now, the Department of Energy stores more than 50 million gallons of high-level radioactive waste in 177 underground tanks at Hanford.

The board's information on the state of nuclear safety of the Hanford site was in response to a request for the board's perspective on site cleanup from U.S. Senator Ron Wyden, D-OR, who is chairman of the Senate Energy and Natural Resources Committee.

Old, Leaky Tanks

Many of the old, single-shell tanks that store radioactive waste are known to leak, so the DOE transferred most of the liquid waste into newer, double-shell tanks. However, in August 2012, the DOE discovered that a double-shell tank was leaking.

The nuclear board said this "reinforces the need to retrieve and treat the tank waste and be vigilant in maintenance and safe operations." Prolonged storage in these tanks poses a "potential threat to public health and safety," the board stated.

But retrieving the waste won't be easy because of the "sludge-like" consistency of some of it and the large plutonium particles it contains.

In addition, there are concerns that hydrogen gas in the tanks could deflagrate and spread radioactive waste. In September 2012, the board sent a letter to the Secretary of Energy, making recommendations for a gas safety strategy and identifying concerns with the DOE's administrative controls for monitoring the flammable gas conditions.

DOE's safety analyses show enough flammable gas in many of the double-shell tanks to reach flammable conditions without proper ventilation, the board said.

The Waste Treatment and Immobilization Plant has raised a number of concerns over technical issues and design flaws, the nuclear board said.

Plant Design Concerns

According to the board, the DOE has not resolved several technical issues with the Waste Treatment and Immobilization Plant, which is now moving from a design-construction phase to a construct-operate phase.

From 2010 to 2012, the board sent several letters to the DOE's senior advisor for environmental management, assistant secretary for enviromental management, and acting assistant secretary for environmental management.

One of the issues, dealing with mixing in process vessels, was "of such significance" that the board sent a recommendation to the Secretary of Energy in December 2010. The recommendation said that inadequate performance of the mixing systems could "lead to nuclear criticality accidents, explosions of flammable gases, and mechanical failures of process vessel components."

The DOE has since told the board that it is developing a revised implementation plan after finding that its original was not supported by test data, further delaying a resolution.

Other concerns that the board has expressed to the DOE regarding the plant include:

The current design of the slurry pipeline system is susceptible to sliding beds of solids forming on the bottom of the pipe, which could increase wear from erosion/corrosion and increase the chance of pipeline plugging leading to a pump failure;

There are several issues that could affect the operability and safety of the electrical distribution system;

Wear allowances in design information "[do] not provide confidence" that piping, vessels, and components in black cells will be able to perform their safety functions over the 40-year design life;

Safety-related controls for ammonia storage do not adequately protect workers for facilities;

There are technical issues with the heat transfer calculations used to establish post-accident hydrogen mixing requirements necessary to prevent explosions;

There are technical issues with the model for estimating radiological consequences to the public from spray leak accidents; and

A 2010 change in safety strategies for hydrogen hazards in pipes and ancillary vessels that allows hydrogen explosions in piping under certain conditions does not have a well-developed Quantitative Risk Analysis to demonstrate that the explosions won't lead to a breach of the primary confinement.

The board noted that the DOE had developed, or was developing, new plans and hazard analysis methods for most of these concerns. However, the department has not yet incorporated new information for the current design of the slurry transport system, the board said.

The nuclear board received a letter from a former engineer on the treatment plant project who alleged a "flawed safety culture."

'Flawed' Safety Culture

In the summer of 2010, the board investigated the safety culture of the waste treatment plant project after receiving a letter from Dr. Walter Tamosaitis, a former engineering manager for the project's contractor.

Tamosaitis alleged that he had been removed from the project after he identified technical problems that could affect safety; he also alleged a "flawed safety culture at the project."

The board's investigation concluded that the "flawed safety culture" at the plant was inhibiting the resolution of technical and safety issues. In June 2011, the board sent a recommendation to the Secretary of Energy stating that the DOE needed to "expeditiously make major improvements in the safety culture" at the plant.

The DOE's Office of Health, Safety and Security independently reviewed the safety issues and issued a report in January 2012 that confirmed the board's findings.

The DOE has now taken several actions to address the safety culture issues, according to the board. These steps include clarifying roles and responsibilities in the federal field and headquarter organizations; strengthening the Differing Professional Opinion and Employees Concerns processes; validating the basis for the project's nuclear safety strategy; and increasing the DOE's senior leadership involvement in technical challenges.

DOE Pursues Safety

The secretary and deputy secretary for DOE issued a memo to all department heads in December 2011 addressing expectations for nuclear safety and stating their commitment "to a strong and sustained safety culture, where all employees—from workers with shovels in the ground to their managers all the way up to the Secretary and everyone in between—are energetically pursuing the safe performance of work, encouraging a questioning work environment, and making sure that executing the mission safely is not just a policy statement but a value shared by all."

While the board praised the secretary for taking on the issue, it noted that "progress in changing any organizational culture is historically slow."

According to the board, the DOE has said it will conduct a review of the plant's safety culture within the next few months to evaluate its corrective actions.

The DOE's official documents related to site cleanup, safety standards, and more are available online. However, the DOE notes that there are "literally thousands of official documents associated with the current cleanup work" and posting all documents since the plant opened "would be unrealistic."